Hi all having a look at some data logs on my 5.3 LS turbo/glide setup
just trying to suss the slippage of the converter .
im comparing rpm on the data log to my gps speedo at shift points.

6700rpm in first im doing 80.5mph
after i shift rpm drops to 5600
and take it up to 5800rpm before backing off.

so first gear shows a 5-6% slippage just using a online calculator .
but second would be way out ,
can you really only measure at high rpm or is something off ??
thanks

 

Assessing slippage at 56 or 5800 is not a good idea if you'll be spinning the motor to 6700+
If you were to rev 2nd gear out to the same rpm as 1st, you'd likely see the same, or less, "slip"

 

Can you post your datalog file? I'm assuming you are using HPT?

 

Holley EFI i dont think i can upload to here

 

I have V5 and I'm familiar with the software. do you mind emailing it to me?
dalton@ftiperformance.com

 

Finally got the datalog open... here is what you need to do to assess converter slip percentage before you make any changes.
1. Make a CLEAN, pass. Your datalog shows TPS dropping during the run whether intentional or not. Make sure your foot stays down the entire run. If it is and that TPS issue persist, you have an underlying issue. ( i added a screen shot of your datalog showing this)
2. Make a FULL pass. top of the run is where we want converter slip to closest to zero. as the car gains momentum throughout the run that slippage should decrease. So ending the run early can present a converter that is too loose even though it isnt. (This is no different than a 1/4mi car showing 20% in the 1/8 but only 3-4% in the 1/4)
3. Make your test hits at the track if possible. It will be much easier to make sure your datalog info lines up correctly and ACCURATELY with your run info(using time in the datalog and time from the time slip)

The above info will get you most of the info you need to assess converter slip. The rest is just info on the car like gearing and tire size.

Don't forget to come back here with your results!